[Cryptography] Data remanence on solid state storage

[Andrew Whalley]

On Thu, Aug 8, 2024 at 9:49 PM Alfie John via cryptography <
cryptography at metzdowd.com> wrote:
> I'm guessing nothing can be guaranteed unless you can address ALL cells
(including
> wear-levelled cells) to verify what's actually stored while also making
sure it's
> not giving you an optimised zero'd block etc.

iOS devices go to some lengths to obtain such guarantees. Their NAND system
provides a small amount of storage that can be securely erased,
called Effaceable Storage:

"A dedicated area of NAND storage, used to store cryptographic keys, that
can be addressed directly and wiped securely. While it doesn’t provide
protection if an attacker has physical possession of a device, keys held in
Effaceable Storage can be used as part of a key hierarchy to facilitate
fast wipe and forward security."

See:
https://support.apple.com/guide/security/data-protection-sece8608431d/web

- Andrew
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